Method of and apparatus for treating textile strands



April 1961 E. c. NEU ET AL 2,977,745

METHOD OF AND APPARATUS FOR TREATING TEXTILE STRANDS Filed May 15, .1958

,u EUGENE C. Neu and JAMES W. DANE-L INVENTORS ATTORNEYS United States Patent 'METHOD OF AND'APPARATUS FOR TREATING TEXTILE STRANDS Eugene C. Neu and James W. Panel, Charlotte, N.C., assignors to Hudson Hosiery Company, Charlotte, N.C., acorporation of North Carolina Fired May 13, 1958, Ser. No. 734,900

[ Claims. c1. s7,--s4

, This invention relates to the treatment of a textile strand or yarn and more particularly to a treatment whereby the exterior surface of the strand is smoothed to remove any irregularities on the surface thereof.

As iswell known, the application of, twist to a composite yarn strand produces a rough surface on the strand which is caused by the individual filaments of the yarn following a spiraled path along the surface of the strand.

primarily to iron or. smooth the surface of a twisted yarn strand, in many cases where the yarn is a synthetic ther moplastic type, the heat of the itching element may be utilized to set twist, shrink the yarn or for other purposes. Some of the objects of the invention having been statedf other objects will appear as the description proceeds when taken in connection with theaccompanying drawings, in;which-- Figure 1 is a fragmentary front elevation showing one section of one type of strand processing machine with which the present strand smoothing apparatus may be associated; V

Figure 2 is a vertical sectional view through one sec tion of the strand processing apparatus, looking atthe right-hand side of- Figure 1;

Figure 3 is an enlarged isometric view of the apparatus shown in Figures 1 and 2, to further illustrate the path of travel of the strand;

Figure 4 is a greatly enlarged fragmentary view of :1 section of knit fabric formed with'a twisted yarn strand which has not been smoothed in accordance with this invention;

Figure 5 is a view similar to Figure 4 except showing the appearance of the stitch loops when the fabric is formed with a twisted yarn strand which has been smoothed in accordance with this invention.

to maintain a uniform twistina' twisted strand of yarn having a rough exterior. because the roughened surface will engage yarn guides and the:like in a non-uniform manner and back up the twist until the twist overcomes the; resistance of the guide and then it will'release itself soythat the yarn strand no longer has uniform twist throughoutits. length,

Atternpts 1havebeen made to overcome'the disadvan-' tages of processing a rough surfaced twisted yarn strand by applying a size material to the strand in order to fill in the low portions and-smooth the surface of the yarn. The size does provide a smooth surface on the strand but has several disadvantages. The most serious disadvantage is that the size may be scraped off the yarn and accumulates on any part against which the yarn passes and quently, Occasionally the accumulations of size will be carried along by the strand to causevariations in tension in the strand and when carried into the fabric the accumulation of size causes deformities therein. Another important disadvantage of applying size to the strand is that the size must beremoved after the fabric is completed.

With the foregoing in mind, it is the primary object of this invention to provide 1 an apparatus for and a method of smoothing the surface of a yarn strand so that the yarn 'may be more easily maintained under uniform tension during subsequent processing operations and provide a more uniform fabric produced therefrom.

f It is another object of this invention to providean apparatus for smoothing the surface of a running strand which may be easily and economically applied to. existing strand processing machinery with very minor modifi-v cation required. 7 a

It is a more specific object of this invention to provide a heated ironing apparatus for a strand twisting machine with means to lead the strand into engagement with the itching element, and-means to move the strand while it is passing'over. the ironing elem'entso that the complete surface of the'strand will. be contacted by the ironing element. While the heated ironing element is provided causes the strand Y to be rolled as it passes in engagethese accumulations ofsize have to be cleaned away fre Referring to the drawings and particularly to Figures lthrough 3, the present invention is shown in association with a conventional up-twister having a supply bobbin 10 rotated at a predetermined speed by a belt'll engag-j' ing a spindle 12 on which the bobbin 10 is mounted. A;

strandjY of yarn is fed from the bobbin 10 and travels upwardly therefrom through a pigtail yarn guide 13 suit-'- ably secured on a fixed support 14. The' strand Y is then processed in accordance with this invention, in a manner to be later described, then'passes over a traversing yarn. guide 16 fixed on atraversing rod or bar mech anism 17 adapted to guide the strand Y as it is woundonto a take-up bobbin 20 which is rotated by engage-. ment with a driving roll 21. The parts of the up-twister heretofore described are conventional parts and it is with ing therethrough. The yarn guide wire 22 and heated.-

pipe'23 are disposed between the pigtail yarnguide. 13 and the traversing guide 16 and it is preferred that the strand engages the left-hand side (Figures 1 and 3); of the lower outermost end of the guide wire 22 and completely encircles the heated pipe 23 before it engages:

the traversing yarn guide 16.

As the strand Y is drawn from the bobbin 10 to the take-up bobbin 2% it is pulled over theheated, n0n-;

rotating pipe 23 and as it is pulled over the same the traversing movement of the bar 17- will impart like rnoyement to the yarn guide wire 22.- Thus, the strand-Q6 surrounding thepipe 23 will be moved transversely along.

the heated pipe 23 as the strand Y is pulled over the pipe 23.

While itis not known exactly what. influence theheated pipe has on the physiochemical properties of strands of every type yarn, synthetic'and'jnatural, it is believed that the heated pipewould act as an'iron to smooth the 's. j

face of any type'st'ra'n'd' passed therearound' or in enga ment therewith. The traversing yarn guide wir 'e I Patented; Apr. 4,. 19 61 ment with the heated pipe 23 to insure that the complete periphery of the strand is smoothed or ironed to remove any irregularities or roughness thereon. The degree of smoothness achieved by this invention would depend upon the type of yarn being processed andtthe amount of heat transferred by the ironing element.

It is known that a smooth surfaced yarn strand produces a much more even and uniform fabric when knitted or woven than a yarn which has a rough surface. Any uneveness of the stitch loops produced in knitting sheer fabric, such as ladies fine gauge sheer hosiery, is easily detected.

Since the leg and foot portions of most ladies hosiery are presently being knit of monofilament yarn, which is relatively smooth, there is little stitch distortion or unevenness caused by roughness of the yarn in these portions. However, the yarn used in knitting the welt is usually a heavier denier multifilament yarn which is twisted and steamed to set the twist and shrink the same before knitting. The type of multifilament welt yarn has been found to be very rough on its surface and will result in uneven stitch loops when knitted, as illustrated in Figure 4. It has been found that when the principles of the present invention are used to process a twisted multifilament welt yarn, the resulting knitted welt fabric has an excellent appearance because of the uniformity of the stitch loops, as shown in Figure 5, and the welt fabric will have better stretching qualities since the yarn forming the stitch loops can slide easily. The fabric will also return to its original position after stretching by wear or laundering because the smooth yarn forming the stitch loops provide better recovery properties in the fabric.

The following example is illustrative of a specific application of this invention to a particular type of multifilament yarn adapted for use as a welt yarn in knitting the upper portion of sheer knit ladies stockings but should not be construed as limiting this invention to this particular use.

' Example A SO-denier nylon strand having 17 filaments twisted together approximately to /2 turn per inch is first transferred or unwound from the pirn, on which it was supplied by the manufacturer, and wound onto a twister supply bobbin on conventional winding machinery without adding any further twist. The twister supply bobbin is then placed on the spindle 12 of an up-twister (Figures 1, 2 and 3) and fed to the take-up bobbin 20 after the surface is ironed smooth by engagement with the heated pipe 23, in the manner previously described;

In this instance, the spindle 12 is rotated at a speed of 10,000 rpm. and the yarn or strand Y is taken up on the bobbin 20 at the rate of 49 yards per minute to thus apply seven turns per inch twist to the strand Y. In this case, the outside diameter of the heated pipe 23 is approximately 1% inches with the outer periphery of the pipe being polished relatively smooth and its surface temperature being maintained at approximately 275 F.

In this case, since the yarn is thermoplastic and the heat is sufliciently high, the twist in the yarn will be set and the yarn shrunk approximately two percent. Thus, the heated pipe 23 serves three purposes in this instance, sets the twist placed in the strand, shrinks the strand and smoothes the surface of the strand. The take-up bobbin 20 is then placed on a winding machine and the strand Y is unwound from the take-up bobbin 20 and wound onto suitable cones in preparation for knitting. In this winding operation, no additional twist is placed in the yarn nor is any size material placed on the strand.

The cones of smoothed, set and shrunk welt yarn are then used to knit the welt of a conventional ladys stocking on a circular seamless knitting machine while the remainder of the stocking is knit with a light denier monofilament yarn in a conventional manner. After the stocking is completed and in what is known as the greige,

it is tested to determine the stretchability of the welt in a coursewise direction. In order to compare the stretchability of this welt with a welt which is knit of identical yarn which is set and shrunk but not smoothed, the welts of both stockings were stretched on a machine constructed for this purpose and it was found that the welt knit of the smoothed yarn would extend to 13 inches and the welt knit of the unsmoothed yarn would extend to 12% inches on the same stretch testing machine.

These two stockings were then dyed and finished in the conventional manner and again tested for stretchability. In this test, the stocking knit with the smooth yarn in the welt would stretch 13 inches while the stocking knit with the unsmoothed yarn in the welt would only stretch 12 inches. It is believed that the welt having the smooth yarn would stretch further after finishing because the yarns in each stitch loop could slide easily relative to each other and thus let the fabric extend to its fully extended position uniformly (Figure 5). On the other hand, the stretchability of the welt having the rough surfaced yarn (Figure 4) would be restricted since the roughness of the yarn would cause resistance to movement of the yarns relative to each other and stretchability of some portions of the welt would be greater than others so that the fabric would not be stretched uniformly.

The yarn made in accordance with this invention has also been tested to determine the elongation and strength thereof and the results compared with an identical yarn which has not been smoothed but which has been steamset and shrunk in a steam cabinet. These tests were made on a conventional yarn testing machine which includes a means for measuring the pull required to break the yarn and means to measure the amount stretched before the yarn breaks. In the case of the conventionally processed unsmoothed yarn, 212 grams of pull were required to break the yarn and it stretched 1% inches before breaking. In the case of the smoothed yarn processed in accordance with this invention, 227 grams of pull were required to break the yarn and it stretched 2% inches before breaking. Thus, this test indicates that the smoothed yarn is stronger and has better stretchability than the conventional processed unsmooth yarn.

The appearance of the welt of the stocking knit with the smoothed yarn is much more pleasing than the appearance of the stocking formed of the non-smoothed or conventional welt yarn and this may be compared by referring to Figures 5 and 4 respectively. It will be noted that the smoother surfaced yarn, shown in Figure 5, forms more even stitch loops and they are positioned in straight vertical wales and straight horizontal courses to aline with each other more perfectly than the stitch loops knit of the unsmoothed yarn shown in Figure 4.

It is believed that the more uniform stitch loops, shown in Figure 5. are the result of several factors. The smoothed yarn will be fed to the knitting instrumentalities under uniform tension at all times and a smooth surfaced yarn will slide in the books of the needles and over the sinkers to form uniform stitch loops each time the needles are drawn down to stitch loop forming level. A smooth surfaced yarn will pass through the various yarn guides and tension devices on the knitting machine in an even flowing manner whereas a yarn which has a roughened surface would tend to drag or hang on the roughened surfaces and at times be slowed down by the roughness thereof. As heretofore pointed out, the twist (seven turns per inch) is set by the heated pipe 23 as the yarn passes therearound and this twist is more even than it would be if the twist were set at a later time since in this case it does not have a chance to untwist or become uneven before it is set.

The example given above illustrates one specific application of the principles of the present invention and,.

orironed and it s not essential thattheilieat applied to theyarnIbe' high enough'to'set and shrink the same as long as it is high enough to smooth the surface of the yarn. There may also be cases where it is beneficial to apply'theprinciples of this invention and smooth the surface of strandsof natural yarns, such as cotton, to facilitate handling the strand during weaving, knitting,

etc. l

l e n en ion is described f u with m filament twisted yarn strand, there may be instances where it would bebeneficial tosmooth the surface of a monofilament yarn. The strand Y may engage only a portion ofthe periphery of the heated pipe 23, the ,complete periphery when wrapped around the pipe one time as shown or more than the complete periphery by wrapping the strand Y around the pipe more than one time. heated pipe may be varied as desired.

It is thus seen that an apparatus for and a method of treating textile strands have been provided wherein the strand is passed in engagement with a heated element while being moved transversely of its path of travel to roll the same, insuring that the yarn is engaged on all surfaces thereof to smooth the outer surface of the yarn in an ironing operation. The heat applied may be varied with certain yarn so that'additional operations may be simultaneously carried out along with the ironing operation, such as heat-setting a synthetic thermoplastic yarn and shrinking the same to the desired degree.

In the drawings and specification there has been set forth a preferred embodiment of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being defined in the claims.

We claim:

1. A method of smoothing the surface of a thermoplastic yarn strand in a continuous process which comprises the steps of running the yarn from a supply to a take-up at a predetermined speed, passing the running yarn completely around and in engagement with a heated element positioned between the supply and take-up, and moving the running yarn transversely of its direction of movement while in engagement with the heated element.

2. A method of heat-setting, shrinking and smoothing the surface of a twisted multifilament thermoplastic yarn strand in a continuous process which comprises the steps of running the yarn from a supply to a take-up at a predetermined speed, passing the running yarn completely around and in engagement with a heated element positioned between the supply and take-up, and moving the running yarn transversely of its direction of movement while in engagement with the heated element.

3. A method of processing a multifilament thermoplastic yarn strand in a continuous process which corm prises the steps of running the 'yarn from a supply to a take-up at a predetermined speed, applying twist to the yarn as it is removed from the supply, passing the twisted running yarn completely around and in engage ment with a heated element positioned between the supply and take-up to heat-set the twist in the yarn and to shrink the same, and moving the running yarn transversely of its running direction while in engagement with the heated element.

4. Apparatus for smoothing the surface of thermoplastic yarn in'a continuous process which comprises a yarn supply source, driven yarn take-up means onto which said yarn is wound from said supply source, an elongated heating element positioned between said supply source and said take-up means, said heating element being positioned with its longitudinal axis perpendicular to the path of travel of said yarn and in engagement with the yarn, and movable yarn guiding means engaging said yarn adjacent said heating element to traverse said yarn Thus, the length of time the strand engages the in a direction parallel-with the longitudinal axis '0! said.

heating element'while the yarnis in engagement with saidv Ya a d y pa s ng ar nd n e g ge nt with said heating element, and movable yarn guiding means engaging said yarn adjacent said heating element to traverse said yarn in a direction parallel with the longitudinal axis of said heating element while the yarn is in engagement with said heating element.

6. Apparatus for twisting, heat-setting, shrinking and smoothing the surface of multifilament thermoplastic yarn in a continuous process which comprises a yarn supply source, yarn take-up means onto which said yarn is wound from saidsupply source, means for driving said yarn supply source and said take-up means to impart twist in said yarn, an elongated heating element positioned between said supply source and said take-up means, said heating element being positioned with its longitudinal axis perpendicular to the path of travel of said yarn and in engagement with the yarn to set the twist in said yarn and shrink the same, and movable yarn guiding means engaging said yarn adjacent said heating element to traverse said yarn in a direction parallel with the longitudinal axis of said heating element while the yarn is in engagement with said heating element to roll the yarn against said heating element and smooth the surface of the yarn.

7. An apparatus for twisting, heat-setting, shrinking and smoothing the surface of mutifilament nylon yarn in a continuous process comprising a yarn supply bobbin, a yarn take-up bobbin, means for driving said yarn supply bobbin and said yarn take-up bobbin to run said yarn from said supply bobbin to said take-up bobbin while imparting twist to said yarn, a heated pipe positioned between said supply bobbin and said take-up bobbin, said pipe being positioned with its longitudinal axis perpendicular to the path of travel of said yarn, said yarn passing around and in engagement with said pipe, the temperature of said pipe being suflicient to set the twist in said yarn and shrink the same, a yarn guide positioned adjacent said pipe, and means to traverse said yarn guide in a direction perpendicular to the path of travel of said yarn to roll the yarn against said pipe and smooth the surface of the yarn as it passes around said pipe.

8. An apparatus for twisting, heat-setting, shrinking and smoothing the surface of a SO-denier l7 filament nylon yarn in a continuous process comprising a yarn supply bobbin, a yarn take-up bobbin, means for driving said yarn supply bobbin and said yarn take-up bobbin to run said yarn from said supply bobbin to said take-up bobbin while imparting about seven turns per inch of twist to said yarn, a heated pipe positioned between said supply bobbin and said take-up bobbin, said pipe being positioned with its longitudinal axis perpendicular to the path of travel of said yarn, said yarn passing around and in engagement with said pipe at the rate of about 49 yards per minute, the temperature of said pipe being about 275 F. to set the twist in said yarn and shrink the same, a yarn guide positioned adjacent said pipe, and means to traverse said yarn guide in a direction perpendicular to the path of travel of said yarn to roll the yarn against said pipe and smooth the surface of the yarn as it passes around said pipe.

9. A method of processing a yarn strand in a continuous process which comprises the steps of running the yarn from a supply to a take-up at a predetermined speed, passing the running yarn around and in frictional engage 7 ment with a heated element positioned between the supply and take-up, and moving the running yarn transversely of its direction of travel as the yarn is engaged by the heated element while transmitting suflicient heat to the running yarn to smooth the surface of the same.

10. A method of processing a twisted multifilament thermoplastic yarn strand in a continuous process which comprises the steps of running the yarn from a supply to a takeup'at a predetermined speed, passing the running yarn around and in frictional engagement with a heated element positioned between the supply and takeup, and moving the running yamttransversely of its direction of travel as the yarn is engaged by the heated element while transmitting sutficient heat to the running yarn toheat-set, shrink and smooth the surface of the same.

' References Cited in the file of this patent UNITED STATES PATENTS' 1,216,147 Lipps Feb. 13, 1917 2,104,809 ODowd Jan. 11, 1938 2,156,244 Mahoney Apr. 25, 1939 2,202,031 Smith May 28, 1940 2,336,100 Jacque Dec. 7, 1943 2,448,743 Solliday et a1. Sept. 7, 1948 

